Hormones and Pheromones

Neurons are not the body's only chemical messengers. The endocrine system communicates through hormones, chemicals released by glands directly into the bloodstream that travel throughout the body to influence distant target organs. Where neurotransmission is fast and localized, hormonal signaling is slower but longer lasting and more widespread. This lesson examines how hormones shape behavior, and considers the more controversial idea of pheromones, chemical signals passed between members of the same species.

The endocrine system includes glands such as the adrenal glands, which sit atop the kidneys, and the pituitary and hypothalamus in the brain, which coordinate the whole system. Hormones influence a remarkable range of behaviors, including stress responses, bonding, aggression, growth